Heart rate monitor

Could be due to so-called cadence lock. Please open the HR graph in full screen mode, and select overlay with cadence, and then post it here.

The bigger GI2X will be more prone to the cadence lock than the lighter GI1, due to its inertial mass and size. Adjusting the tightness of the strap may help, but for any serious training I recommend getting a chest strap HRM anyway. The wrist HRM will never be as accurate as a chest HRM, and things like HRV, LTHR, breathing rate, activity stress cannot really be measured by the wrist sensor.

Thank you for your answer. I am attaching photos. It is surprising that this problem did not occur at the beginning of owning the GI2XS

I will add that I have more such stranger charts

Yes, to me it looks indeed like the cadence lock.

Jazieek said:

It is surprising that this problem did not occur at the beginning of owning the GI2XS

Either a coincidence, or it could be also due to the cooling weather causing a certain level of vasoconstriction, and hence weaker optical signal for the sensor. Could be also because you did not tighten the wristband tight enough (or oppositely it was too tight). And it could also be that the latest firmware has a modified algorithm for filtering out the false signal caused by the cadence (which is always present to certain degree). What may work well for ones, may get it worse for others. 

If you suspect the firmware causing it, you can try downgrading the firmware (you would have to side-load it from the previous beta installation package). However, I would still recommend getting a chest strap as the simplest and the most reliable solution. The best is HRM-Pro because it comes with a lot of added functionality (including Running Dynamics), but if it is not within your budget, there are plenty of inexpensive chest straps from other manufacturers.

Any tips on how to "fix" it?

As written previously:

• best fix: chest strap HRM
• adjusting the tightness of the wristband
• try downgrading the firmware

I will probably go back to the previous software, looking back the graph is not much different and the heart rate is correct. thank you for your time and all your tips.

new soft and tighter strap...

Maybe you will have to reset your heart rate zones and maxHR cause they could be messed up if you had erroneous readings..